In an article entitled "The Beckman Rearrangement of -Dihydrocembellulone Oxime", Journal of the American Chemical Society, 79, 3756 (1957), W. D. Burrows and R. H. Eastman report the synthesis of 4,5,7,7a-tetrahydro-7a-isopropyl-4-methyl isoxazole[5,4-b]-pyridin-6(32H)-one (XIV) by nitrosation of 5-methyl-1-isopropyl-2-azabicyclo[4.1.0]heptanon-3 (V). This reaction is represented as follows: ##STR3## No pharmacological or other utility is noted for the product XIV.
Applicant, on the other hand, has discovered that 3a,4,7,7a-tetrahydro3,6,7a-trimethyl-4-substituted phenylisoxazolo[5,4-b]pyridine-5-carboxylates of Formula I may be obtained by treating the corresponding 5-acetyl-1,4-dihydro-2,6-dimethyl-4-substituted phenyl-3-pyridinecarboxylates of Formula II with hydroxylamine in pyridine. Applicant has further discovered that said isooxazolo[5,4-b]pyridines of Formula I exhibit calcium antagonist and antihypertensive properties as shown in standard pharmacological procedures.